Would you be able to show some other views of the space?

I can see a desk office but what do you want from it as a den?

I would look at built ins or using file cabinets and doors or whatever for your budget to create 2 L shaped area for the desks.

I posted the following video on another thread. I thought this showed many good ideas for a study/den.

Here is a link that might be useful: Christopher Lowell

We converted a 12' x 15' bedroom into a two person office + den. I'm posting our final layout to give you one possibility. I recommend really focusing on the use of the space. We needed a long counter for crafts, a lot of book storage and a comfortable place to watch tv. DH sits in his comfy desk chair and I use the chaise when we watch tv.
Lisa

Have you thought of a partners desk?

where can you purchase these desk